Serum complement (often referred to simply as complement) is known in the art to be a highly complex system of approximately at least nine different serum proteins found in mammals. In the body, complement operates in a cascade fashion to destroy the outer cellular membrane of an immunological-invading agent.
However, outside of the body it is highly unstable. Aqueous solutions of complement become useless within a day, even when stored at 4.degree. C. In the past, complement was stabilized in two ways. It was either frozen or lyophilized.
The need for greater stability for complement solutions has increased because it is used now as a key component in diagnostic assays. For example, U.S. Pat. No. 4,483,921 to Francis X. Cole describes a liposome-based immunoassay which uses complement to lyze, i.e. break open, holes in the walls of liposomes. Before the present invention, the user of such an assay had to prepare their complement solutions daily in order to practice such an assay.